Is this ok to do? It's for a half-bath vanity sink. The wall connection is RIGHT above the bottom of the vanity cabinet, so if I can plumb everything above the bottom of the vanity cabinet, I can avoid cutting through it.
Ok thanks. Any alternative configuration that will work then? Or is the only option to cut into the vanity cabinet bottom so I can “go downward” with the drain pipe?
If you add an AAV after the trap, that would also work. Breaking the siphon on the drain prevents sewer gas from entering the home. Nobody wants to brush their teeth above a smelly septic smell as you're getting ready for work.
Sometimes people raise the drain in the wall too.